Hydraulic assembly

ABSTRACT

A hydraulic assembly including a reservoir, a pump arrangement, hydraulic control elements, and an electric motor for the pump arrangement whose components are coaxially arranged along a straight axis, possibly overlapping one another partially, is constructed having smaller dimensions and with simpler construction. The pump arrangement is therefore an axial piston pump ( 2, 2   a   , 5, 6 ) whose cylinder block ( 2 ) is oriented coaxially to the other components and the cylinder block ( 2 ) is provided with several pump elements ( 6 ).

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a hydraulic assembly comprising a reservoir, a pump arrangement, hydraulic control elements, and an electric motor for the pump arrangement whose components are arranged coaxial along a straight axis, possibly partially overlapping one another.

2. The Prior Art

EP 1 302 660 A2 discloses a fuel pump designed as an axial piston pump inserted into the fuel tank of a vehicle. The motor for the pump is arranged coaxial in this pump arrangement; however, the pump itself is installed as one unit in the much larger fuel tank as it is necessary for hydraulic assemblies of this type without especially explaining, for example, the specific geometric constellation thereof. The aforementioned independent assemblies without an electric power supply for the electric motor are generally known in the art and they are employed increasingly for transportable purposes and/or for generating small forces, as for example in connection with the hydraulic actuation of motor vehicle tops or the movement of medical treatment chairs or the like.

DE-C3 32 27 926 proposes in this respect to arrange a pressure-free gear pump on one side of a base section and to arrange the sealed, encapsuled pump motor on the other side of said base section. The inner space remaining in the motor housing can also be used as a reservoir through a connecting opening in the base section.

An assembly is additionally disclosed in EP-A1 0 628 720 wherein a first elongated reservoir for the hydraulic medium is arranged on the base section in axial direction in connection with a radial piston pump whereby the motor shaft sealingly reaches into the reservoir and extends through said reservoir to the pump. The reservoir must be constructed thereby of relatively rigid and heavy material. EP-A1 0 690 230 discloses an assembly in which the motor projects into the reservoir that is arranged coaxially. EP-A1 0 857 871 discloses an assembly housing having also a radial piston pump with an annular reservoir surrounding the tubular encapsuled electric pump motor.

The object of the present invention was to provide an assembly with smaller dimensions and simpler construction. Better economic viability and lower costs are to be achieved through a higher degree of integration.

SUMMARY OF THE INVENTION

For the achievement of this object it is proposed according to the invention that the pump arrangement is an axial piston pump whose cylinder block is oriented coaxial to the other components whereby said cylinder block is provided with several pump elements. The axial length of the assembly made necessary by the dimension of the reservoir can be optimally used and the diameter can be kept considerably smaller compared to other pump designs, particularly in comparison to gear pumps or radial piston pumps used mostly in assemblies of this type.

An additional decrease in size or the optimal use of the existing structural space is possible according to a preferred embodiment variant whereby the cylinder block is provided with magnets about its circumference and whereby it is designed as a rotor of the electric motor. A motor separate from the pump can thereby be eliminated and its structural space is saved thereby.

The magnetized coils of the electric motor are thereby advantageously arranged around the cylinder block within the housing of the assembly.

The arrangement of connecting lines and the design of the hydraulic elements can be simplified in that the reservoir and the cylinder block are arranged on the same side, preferably essentially coaxially relative to the space of the hydraulic control elements.

Additional simplification of the hydraulic line arrangement is made possible through a characteristic of the invention whereby the cylinder block is rotatably mounted on a tube and whereby the tube extends from space containing the hydraulic control elements and reaches into the reservoir of the assembly with a suction opening.

The reservoir and the space of the assembly housing containing the cylinder block is advantageously separated by a partition. The suction opening for the hydraulic fluid can be moved thereby to a space where the hydraulic fluid cannot undergo swirling and foaming through the rapidly moving axial piston pump.

A more stable mounting for the cylinder block of the pump can be achieved if the tube is advantageously mounted in the partition whereby the pump is at the same time the rotor of the electric motor.

The known advantages of a normally complicated suboil motor can be achieved in a simpler manner with the assembly of the invention in that at least one opening is provided in the partition below the fluid level and at least one opening above the fluid level at the normal operational position of the assembly whereby operational communication is maintained through the openings with the reservoir and the space of the housing containing the cylinder block. A motor can be used thereby having a high capacity at small structural dimensions since heat is carried off by the hydraulic medium flowing around the motor or the cylinder block.

The same advantages can be achieved in an alternative embodiment of the invention wherein the space of the housing containing the cylinder block is at the same time the reservoir.

An additional improvement of the aforementioned construction proposes that at least a few magnetizing coils are covered by fluid or fluid circulates about said coils. The loss of capacity of the coils can be simply minimized through heat dissipation through the hydraulic medium so that high amperage is made possible along with high motor capacity at small structural dimensions.

The aforementioned advantages become especially of importance when in the normal operational position of the assembly the fluid in the reservoir has reached a specific height so that the cylinder block and/or the coils are covered by the fluid at least for the most part.

In view of the simple construction of the assembly of the invention it can be proposed according to an additional characteristic that a wobble plate is mounted on the tube.

An embodiment example of the invention is explained in more detail in the following description with the aid of accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows thereby an axial longitudinal section through an assembly according to the present invention, and

FIG. 2 is a cross section through the assembly of FIG. 1 along line II-II.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The hydraulic assembly of FIG. 1 is provided with a space 1 containing the hydraulic control elements whereby said space 1 forms the base section of the assembly which is provided in a known manner with kidney-shaped control openings for the connecting, preferably reversible axial piston pump. The cylinder block 2 of the axial piston pump is pressed with one of its outer sides onto the space 1 in a coaxial arrangement whereby intake and output elements of the cylinder 2 a are provided on said outer side. The cylinder block 2 is thereby rotatably mounted on a hollow tube 3 whereby the tube 3 starts in the space 1 containing the hydraulic control element and extends with a suction opening 3 a into the reservoir 4, 4 a. In addition, the wobble plate 5 is non-rotatably mounted on the hollow tube 3 advantageously coaxial to space 1 and the cylinder block 2 whereby the wobble plate 5 causes through its slanted front side the axial movement of the piston 6 of the axial piston pump while guided in the cylinder 2 a.

Four magnets 7 are provided in the cylinder block 2 of the axial piston pump so that the cylinder block 2 is at the same time the rotor of a brush-less electric motor. The corresponding windings of the magnetized coils 8 are arranged about the cylinder block 2 within the housing 9 of the assembly. A separate electric motor is thereby not necessary for the axial piston pump since the pump itself serves as its own motor together with the magnetized coils 8.

The magnetized coils 8 and the wobble plate 5 are advantageously connected as one unit through a common carrier piece 18 in the space 1 of the hydraulic control elements. The housing 9 of the assembly can therefore be made thinner and lighter since the mechanical stability is provided by the carrier piece 18 to a large extent.

Space 4 a of the axial piston pump 2, 2 a, 5, 6 is separated by a partition 10 from space 4 of the reservoir in the illustrated embodiment of the assembly whereby the suction opening 3 a of the tube 3 projects into the reservoir. Holes 11 or similar through-going openings are provided in the partition 10 through which space 4 a communicates operationally with the axial piston pump and with space 4 so that hydraulic fluid is present up to a fluid level 12 in both spaces. Level 12 of the hydraulic fluid is at a height so that at least one of the holes 11 a is disposed in the air-filled space of the reservoir 4, 4 a.

At the side of the reservoir 4, 4 a, which is opposite of the axial piston pump 2, 2 a, 5, 6, there is inserted a printed circuit board 15 with control electronics between an additional partition 13 and the cover 14 of the assembly whereby the control electronics control activation of the coils 8 through the connecting lines. The reservoir 4, 4 a is also arranged coaxial to space 1 and the cylinder block 2. The power supply and possible control signals are fed or supplied through the main terminal 17. 

1. A hydraulic assembly comprising a reservoir, a pump arrangement, hydraulic control elements, and an electric motor for the pump arrangement whose components are arranged coaxial along a straight axis, possibly overlapping one another partially, wherein the pump arrangement is an axial piston pump (2, 2 a, 5, 6) whose cylinder block (2) is oriented coaxial to the other components and whereby said cylinder block (2) is provided with several pump elements (6).
 2. An assembly according to claim 1, wherein the cylinder block (2) is provided with magnets (7) about its circumference and whereby it is designed as a rotor of the electric motor.
 3. An assembly according to claim 2, wherein the magnetized coils (8) of the electric motor are arranged around the cylinder block (2) within the housing (9) of the assembly.
 4. An assembly according to claim 1, wherein a reservoir (4, 4 a) and the cylinder block (2) are arranged on the same side, preferably essentially coaxially relative to the space (1) of the hydraulic control elements.
 5. An assembly according to claim 4, wherein the cylinder block (2) is rotatably mounted on a tube (3) and whereby said tube (3) extends from the space (1) containing the hydraulic control elements and reaches into the reservoir (4, 4 a) of the assembly with a suction opening (3 a).
 6. An assembly according to claim 4, wherein the reservoir (4) and the space (4 a) of the assembly housing containing the cylinder block (2) is separated by a partition (10).
 7. An assembly according to claim 5, wherein the tube (3) is mounted in the partition (10).
 8. An assembly according to claim 7, wherein at least one opening (11) is provided in the partition (10) below a fluid level (12) and at least one opening (11 a) above the fluid level (12) at the normal operational position of the assembly whereby operational communication is maintained through the openings (11, 11 a) with the reservoir and the space (4 a) of the housing containing the cylinder block (2).
 9. An assembly according to claim 4, wherein the space (4 a) of the housing containing the cylinder block (2) is at the same time the reservoir.
 10. An assembly according to claim 9, wherein at least a few magnetizing coils (8) are covered by fluid or fluid circulates about said coils.
 11. An assembly according to claim 10, wherein when in the normal operational position of the assembly the fluid in the reservoir (4, 4 a) has reached a specific height so that the cylinder block (2) and/or the coils (8) are covered by the fluid at least for the most part.
 12. An assembly according to claim 11, wherein a wobble plate (5) is mounted on the tube (3). 